Originally considered to be a milder version of bipolar disorder (BD), research now indicates bipolar disorder- not otherwise specified (BP-NOS) is a highly impairing condition. Considerable gains have been made recently in understanding BP-NOS, in large part by research utilizing clear operational definitions for BP-NOS (cf. the NIMH-funded Course and Outcome of Bipolar Youth [COBY] and Longitudinal Assessment of Manic Symptoms [LAMS] studies). However, clinical trials have focused on youth with Bipolar Disorder- Type I (BP1). No clinical guidelines exist for the treatment of BP-NOS. BP-NOS is similar to BP1 and BP2 in terms of peak symptom severity, suicidal ideation, and number of comorbidities; it is similar to BP2 in terms of functional impairment (Axelson et al, 2006). However, youth with BP-NOS are three times slower to recover and experience more mood lability than youth with BP1 or BP2 (Birmaher et al, 2006). They are also more likely to remain sub- syndromal rather than becoming asymptomatic compared to youth diagnosed with BP1 and BP2 (Birmaher et al, 2006). Available evidence-based pharmacotherapy guidelines are for BP1; efficacious medications are, unfortunately, associated with significant risk for adverse events (Kowatch, Fristad, Findling & Post, 2009). Thus, there is a greater imbalance in the risk:benefit ratio of treating these youth with psychotropics compared to the risk:benefit ratio of treating youth diagnosed with BP1, for whom we have clinical trial data. Previous research on diet and nutrition suggests that omega-3 (?3) fatty acids have a beneficial effect on mood, which might provide either a primary or adjunctive treatment with a more favorable risk:benefit ratio for children suffering from BP-NOS than currently available pharmacologic interventions. Psychoeducational psychotherapy (PEP) also has shown promise in treating bipolar spectrum disorders in children aged 8-12 (Fristad, 2006; Fristad, Verducci, Walters, & Young, 2009); its efficacy in treating BP-NOS specifically has not been determined. The current study compares ?3, PEP, and their combination to a placebo supplement and active monitoring (AM) in a 12-week trial of 60 children with BP-NOS (15 each with ?3, ?3 plus PEP, PEP, and placebo, all with active monitoring). Primary goals are to determine: 1) feasibility of a) recruiting 60 participants in 2 years; b) participant retention over a 12-week trial; and 2) placebo-controlled effect sizes for ?3, PEP, and combination treatment on manic and depressive symptoms. Secondary goals are to explore response curves over time, mediators and moderators, treatment response across a broad array of outcome variables, adherence to treatment, impact on physiologic parameters often worsened by mood stabilizing medications, and experience of side- effects in participants receiving ?3 and/or PEP. Comparisons of results to a parallel study of children with depression with identical design will maximize knowledge gained. This pilot study of ?3, PEP, and combined treatment will provide evidence about whether a larger trial is feasible and justified.